Eric seems to like it a lot

My buddy Eric took it out yesterday. He called the ride nimble and supple. He did bottom the suspension a few times, so it's not dialed in yet. I'll try to get a hold of it for a ride at some point and put it through its paces.

There are bearings in the lower
and upper main pivots. Everything else has bolts that act as bushings. I fear for
the longevity of the pivots.

Have any pics of these disassembled? That really doesn't good. I'd seriously consider getting a machine shop to turn up some Delrin bushings and custom bolts for you. I really don't see the pivots lasting too long like that and then you'll be looking at worn pivots that will need to be machined round again.

Also, does front derailleur cable housing anchor into the swingarm? It's hard to tell from the photos, but it almost looks that way.

It certainly looks nice and I'm glad he's happy with it. I'm personally still in the camp of not willing to be an early adopter.

Thanks for fixing the photo

The medium AC-036 only weighed 2040g without shock. That's about 2270 with, which is still almost one third of a pound lighter than the Giant. I'd think you'd drop a lot more building up the Giant to 24 lbs. I can't tell you what I've spent on the Spider to get it to about 26.2 plus I got a great deal on the frame. Also your bike would then say Giant in about 27 places.

Eric likes the frame, there is one linkage which needs some kind of washer to keep it from knocking. It's more of an annoyance. If this frame came down to something like $600 it would be a great ride for the money.

Does anyone else sense something fundamentally wrong with such a chainstay mounted rear disc caliper on a FS bike? From an observational point of view, that's asking for brake jack, since the caliper is clamping the rotor as it's making a downward motion, which would create a force that would also drive the swingarm downward, stiffening the suspension under braking. The typical caliper location creates a force that is up-forward (a little pro brake-squat) at sag and less up and more forward as you get deeper in travel (more brake neutral).

Does anyone else sense something fundamentally wrong with such a chainstay mounted rear disc caliper on a FS bike? From an observational point of view, that's asking for brake jack, since the caliper is clamping the rotor as it's making a downward motion, which would create a force that would also drive the swingarm downward, stiffening the suspension under braking. The typical caliper location creates a force that is up-forward (a little pro brake-squat) at sag and less up and more forward as you get deeper in travel (more brake neutral).

Aside from there being no consensus on what is good and what isn't, this isn't functionally different than many single pivot designs, it's just odd for a design that has a pivot on the "seatstay". Simple swingarm designs are like this.

Aside from there being no consensus on what is good and what isn't, this isn't functionally different than many single pivot designs, it's just odd for a design that has a pivot on the "seatstay". Simple swingarm designs are like this.

I'm criticizing the location of the rear disc brake caliper. It doesn't really matter what suspension design it is, except for a few designs that have lots of rearward travel/axle path. They're all designed to go up, and that brake is directing forces downward. That's the dreaded brake jack that most bikes have been dreading before the days disc brakes became popular.

Niner CVA - the caliper catches the rotor when it is moving forward, which has minimal effect on suspension action. Not sure how CVA looks fully compressed, but considering the relatively vertical axle path of CVA suspension design, I doubt its braking characteristics change much according to where it is in its travel.

Trek ABP - the caliper catches the rotor when it is moving forward, and a little up, having a very slight effect on suspension action, actually make it feel plusher due to the slight brake squat. Due to the arcing axle path, and how the seatstay tilts a little further in its travel range, it becomes more neutral with less braking squat as you get deeper in travel.

Zerode G1 - Here's a bike known to have brake jack. The brake is mounted on the primary swingarm, which is the main arm that goes from the main pivot to the axle. The braking forces pushes forward, while the swingarm wants to arc backwards and upwards. As it gets deeper in travel, the braking forces want to push down and forward, countering the forces that bumps have on the suspension. This is why such high pivot designs typically have floating brakes. See YouTube video clip of how its braking habits change significantly as it goes through its travel and why similar bikes have floating brakes. Australians making things backwards... Sorry, just teasing.

Devinci Wilson - proper disc caliper mounting location for isolating braking forces on high single pivot. The swingarm is not always the chainstay, as seen on the two high single pivots above. Note how the mount comes out to position the brake caliper into a position that catches the rotor during the forward moving part of its rotation for relatively* neutral braking (* still counters the rearward travel/axle path).

Santa Cruz Bullit - Santa Cruz had very limited space to fit this caliper location in, but they put it in a very good spot, before going with a floating brake mount.

Another faux bar. Hoping that people see the pattern.

Fabien Barel's Kona that he won the DH World Champs on. He specifically asked for more brake squat, which is why the floating brake is configured that way--it catches rotor so it has more upward force, which apply forces that would try to compress the suspension or lift the axle. Since this pivot arcs back at first, maybe that was a wise move, as this setup counters that rearward arc even less than a more "neutral braking" setup.

The chainstay mount works for a hardtail, as it only helps to drive the rear end into the ground more, for extra friction between the ground and wheel. In this single pivot application, it works like anti-squat, extending the swingarm. Taking it further than that, my conclusion is the probably not much more credible than others.

Most of the photos you posted aren't "faux bar" like this frame. On a "faux bar", the lower swingarm is where the the caliper needs to be anchored unless the upper linkage shares a pivot with the axle (Trek). Assuming that's where you mount the caliper, it doesn't matter how you orient it. The braking force is going to twist the swingarm in the same direction that the tire is rolling. Mounting the caliper at 12 o'clock or 9 o'clock won't have any impact on how braking compresses the suspension.

I'm criticizing the location of the rear disc brake caliper. It doesn't really matter what suspension design it is, except for a few designs that have lots of rearward travel/axle path. They're all designed to go up, and that brake is directing forces downward. That's the dreaded brake jack that most bikes have been dreading before the days disc brakes became popular.
...
The chainstay mount works for a hardtail, as it only helps to drive the rear end into the ground more, for extra friction between the ground and wheel. In this single pivot application, it works like anti-squat, extending the swingarm. Taking it further than that, my conclusion is the probably not much more credible than others.

I agree with your last sentence, the rest is a joke. You understand brake jack like you understand anti-squat,,,much too poorly to be commenting on it.

On a "faux bar", the lower swingarm is where the the caliper needs to be anchored unless the upper linkage shares a pivot with the axle (Trek).

I thought the main design feature behind split pivot and ABP was not mounting the caliper on the main swingarm, to further isolate braking forces from suspension forces, compared to other single pivots. Who says you *need* to mount it on the "lower" swingarm? Isn't it just because it happens to be a stronger place to put it, for faux bars designs, allowing you to lighten up the seat stays? I'm not saying it should be mounted on the seatstay. It's just the position that looks wrong to me. The designers who mount it between the chainstay and seatstay on hardtails say it improves braking power, but I guess that's more bike industry bullcrap, unless they mean because of greater airflow over the pads. It's in one of the articles about those bikes that I recall reading some comment about how it drives the wheel into the ground for more braking traction.

Originally Posted by car_nut

Assuming that's where you mount the caliper, it doesn't matter how you orient it. The braking force is going to twist the swingarm in the same direction that the tire is rolling. Mounting the caliper at 12 o'clock or 9 o'clock won't have any impact on how braking compresses the suspension.

Do you mind elaborating? Why wouldn't it matter if it's mounted at 12 or at 9 or anywhere else for that matter? If what you say is true, what caused the brake jack of older single pivot/faux bar designs, including designs with rim brakes? I know many confused brake squat with brake jack, but I know some were clear about designs stiffening under braking. Do mind including how your explanation covers designs with floating brakes like the Kona DOPE, Lahar, Bullit, Lawwill, etc.? Also, mind explaining how it works to initiate a nose dive when used in mid-air, if that's relevant?

I'm assuming I'm asking the right guy, who knows of statics and dynamics.

The designers who mount it between the chainstay and seatstay on hardtails say it improves braking power, but I guess that's more bike industry bullcrap, unless they mean because of greater airflow over the pads. It's in one of the articles about those bikes that I recall reading some comment about how it drives the wheel into the ground for more braking traction.

Yes, that would be bullcrap.

Originally Posted by Varaxis

Why wouldn't it matter if it's mounted at 12 or at 9 or anywhere else for that matter? If what you say is true, what caused the brake jack of older single pivot/faux bar designs, including designs with rim brakes?

Mass transfer, the same thing that causes dive in the fork.

Originally Posted by Varaxis

I know many confused brake squat with brake jack, but I know some were clear about designs stiffening under braking.

Squat and jack are directions, not unique phenomena. The rear suspension naturally jacks under braking. The geometry of the rear suspension + brake will generate a force that resists that jacking tendency (though negative values will amplify it). Designers can choose to control this force using a floating brake or they can mount the caliper on the swing arm and let the force be determined by the main pivot. The orientation of the caliper is not what matters.

There is no agreement on the right amount of brake anti-jack as there is with anti-squat. Anti-jack works by unweighting the wheel so benefits come with liabilities.

I've got a good experiment. Flip your bike over, spin the wheel and then grab it with your hand. It will apply a force in the same direction of the wheel rotation, regardless of where you grab on the wheel.

Suspension designs come into play in the direction of wheel rotation while braking. Where the caliper is located is not as important as the design of the suspension itself.

For hardtails, placing the caliper on the chainstay was popular because the chainstays are usually stronger and don't always require frame reinforcement. I prefer seatstay mounted for convenience.

I thought the main design feature behind split pivot and ABP was not mounting the caliper on the main swingarm, to further isolate braking forces from suspension forces, compared to other single pivots. Who says you *need* to mount it on the "lower" swingarm?

Sorry, I don't think I was clear with that. My point was that the caliper needs to be mounted to the same arm that is carrying the axle mount. The reason is so that the caliper isn't moving relative to the disc as you compress the suspension. The Trek ABP is unique in that they place the linkage pivot at the same point as the axle. This gives you the freedom to mount the caliper to either linkage arm. You are correct in stating that the whole point behind ABP is to isolate the braking force from acting on the suspension.

Originally Posted by Varaxis

Do you mind elaborating? Why wouldn't it matter if it's mounted at 12 or at 9 or anywhere else for that matter? If what you say is true, what caused the brake jack of older single pivot/faux bar designs, including designs with rim brakes? I know many confused brake squat with brake jack, but I know some were clear about designs stiffening under braking.

The force on the caliper causes an equal and opposite reaction at the axle. These cancel out. What's driving the suspension to compress (edit: squat) is that you have the wheel spinning and you are now locking the wheel to the swingarm. This makes the swingarm want to rotate in the same direction as the wheel, which compresses it.

The design types with a floating caliper and added linkage attempt to separate these forces and drive the resulting force into the frame, not the suspension.

Hey thanks for the write up and pics.
I'm the guy that got the ebay $639 price before they raised it to $1100 then pulled the frame all together. Happy estore said that they couldnt ship for 5 to 6 weeks and wanted to refund my money. I said "I'll wait". They wrote back "you are the lucky dog...the price is now $1100!"
Hope it shows up. I'll post the progress.
Any news updates on the ride?

Yea, I was wrong from the moment I was thinking the force created from braking was a vector instead of a torque. That experiment won't really help if I'm dead set thinking it's a vector, as I could just explain it as a force that follows a tangent line, perpendicular to a line drawn from the center of the wheel to the point where I grabbed the edge of the wheel. That's sort of the definition of a torque though, with the axis in consideration. I could just conveniently ignore the axis, though.

I realized that soon enough when I had people* raising the bullcrap flag and I bothered to look it up, as it was a simple enough mistake. *specifically car_nut, as craigsj seems to like to ridicule others and argue over semantics more than science. Thanks for the extra explanations though.

Originally Posted by car_nut

The design types with a floating caliper and added linkage attempt to separate these forces and drive the resulting force into the frame, not the suspension.

I guess what I really wanted to know was an in-depth explanation on how the design works on Fabien Barel's floating mount brake, which was designed to induce more brake squat in a controlled manner. I recall a comment saying the brake squat in the rear was intended to balance the bike out with fork dive in consideration. I don't really want to think that is bullcrap. Actually, nevermind, that belongs in another thread.

I guess what I really wanted to know was an in-depth explanation on how the design works on Fabien Barel's floating mount brake, which was designed to induce more brake squat in a controlled manner. I recall a comment saying the brake squat in the rear was intended to balance the bike out with fork dive in consideration. I don't really want to think that is bullcrap. Actually, nevermind, that belongs in another thread.

Well for starters that pic of the Kona above does not show how Fabien ran his rear brake. The Stab has 2 mount holes on the frame and in that pic the floater is mounted to the upper hole, with the lower hole by the BB.

Mounting in the upper hole (as above) gives more neutral braking than mounting to the swingarm itself, as the caliper mount is basically held parallel to the frame throughout the suspension travel, neutrailising any of the rotational force imparted on the caliper when you pull the brake.

The lower hole gives a whole different feel. havnt got time to explain fully just now but ill try and put together some diagrams later. Just to say tho, its VERY hard to ride a bike like this, the extreme squat of this set-up means the rear brake is much less effective (as soon as it gets grip the wheel shoots through its travel, meaning it unwieghts a little and gets less grip!). This set-up is for serious recers only, who can use it to help them squish right into berms by dragging the rear brake on the way in, pre-compressing the rear suspension so they can really pump though the corner and fire out the other side. Not a set-up for the feint harted, one panic brake and you lose all your rear travel, not fun when lending a drop or hitting a rock garden (personal experience!!!)

I realized that soon enough when I had people* raising the bullcrap flag and I bothered to look it up, as it was a simple enough mistake. *specifically car_nut, as craigsj seems to like to ridicule others and argue over semantics more than science. Thanks for the extra explanations though.

I ridicule others who pretend to understand science while passing themselves off as experts. People like you, Varaxis. The more people are informed of your pretense the more they will ignore what you have to say. It's a public service. I certainly don't care whether you learn anything about brake jack since you aren't here to learn in the first place.

Originally Posted by Varaxis

I guess what I really wanted to know was an in-depth explanation on how the design works on Fabien Barel's floating mount brake, which was designed to induce more brake squat in a controlled manner. I recall a comment saying the brake squat in the rear was intended to balance the bike out with fork dive in consideration. I don't really want to think that is bullcrap. Actually, nevermind, that belongs in another thread.

Are you saying you haven't read Foale Chapter 9 or simply that you don't understand it? Hard to believe considering you pretended to have read it in this thread. Understanding these things takes a little more effort than just throwing a few vocabulary words around and then complaining that others argue your "semantics".

Does anyone else sense something fundamentally wrong with such a chainstay mounted rear disc caliper on a FS bike? From an observational point of view, that's asking for brake jack, since the caliper is clamping the rotor as it's making a downward motion, which would create a force that would also drive the swingarm downward, stiffening the suspension under braking. The typical caliper location creates a force that is up-forward (a little pro brake-squat) at sag and less up and more forward as you get deeper in travel (more brake neutral).

this rame looks sic and at 26.5 is pretty light but sayin a spearfish is heavier is kinda silly mines built up at 26.3 on a park tools scale. that being said i dig the look of this rig and would have fun building one up in gloss 12k.Im always lookin for a new build project

As far as I'm concerned it's not flexy

Once begot the upper pivot tightened up the frame is less flexy with a rare QR than my Spider with a 10mm RWS. I think it's a pretty solid frame.

My reservations would be about the pivots where there are bushings rather than bearings. That's a longevity issue, which won't be answered until many miles are put on the frame.

The frame really looks like a Fisher Superfly 100. Obviously not as light. If the price cam down $100 it would be a deal, where it stands now at about $1050 delivered with an RT-3 it's the lightest alternative, with more travel than a sprearfish. The quality of the carbon is great.

Once begot the upper pivot tightened up the frame is less flexy with a rare QR than my Spider with a 10mm RWS. I think it's a pretty solid frame.

My reservations would be about the pivots where there are bushings rather than bearings. That's a longevity issue, which won't be answered until many miles are put on the frame.

So there were DU bushings on the smaller pivots? Not just bare steel bolt-on-carbon action?

Originally Posted by nbwallace

The frame really looks like a Fisher Superfly 100. Obviously not as light. If the price cam down $100 it would be a deal, where it stands now at about $1050 delivered with an RT-3 it's the lightest alternative, with more travel than a sprearfish. The quality of the carbon is great.

I'd consider giving the technical drawing to Push, to let them tune a nice Monarch RT3 for me, and building it up with that...

Not really bushings

The non-bearing pivots have small holy into a nut which has a built in sleeve, which acts like a bushing, but it's not really a bushing in that it doesn't rotate independently of the bolt. I requested some spares with my road frame. When I get them, I'll shoot some pics.

I would say the rt-3 high tune, works pretty well. Clearly a custom tune would be an improvement. If Push can come up with a custom tune, that would be awesome.

The non-bearing pivots have small holy into a nut which has a built in sleeve, which acts like a bushing, but it's not really a bushing in that it doesn't rotate independently of the bolt. I requested some spares with my road frame. When I get them, I'll shoot some pics.

I would say the rt-3 high tune, works pretty well. Clearly a custom tune would be an improvement. If Push can come up with a custom tune, that would be awesome.

Hm, it's those non-bearing pivots that's holding me off... especially the swing link's, as it makes a pretty big rotation. They dont even contain any delrin/teflon composite bushings? Just metal-on-metal?

Push should be able to make a nice tune based on the leverage-graph posted earlier, right?

It's really metal screw on carbon

Those non-bearing pivots are really non-threaded metal on carbon. There's no teflon, also when the frame arrived no grease, which made the suspension impossible to cycle, even without a shock installed.

Did you find that your pivots were greased when the frame arrived?

Have you noticed if you can cycle the pivots manually? When our frame first arrived I couldn't until I lubed all the pivots.

It takes some doing to get the rear derailleur dialed in since at least with the xt e-mount we used the cable clamping bolt was not readily accessible. I also had to adjust the angle of the front der using a couple of washers under the frame mount.

To mount the shock you need the rockshox m8x22.2mm kits for both the upper and lower mounts:

I used m8x40mm bolts for both the mounts. For the upper mount I used a m8 lock nut and for the lower mount nut I MacGyvered something together using a brass threaded insert as shown in the attached image:

I threaded one onto an M8 bolt and put the bolt in a drill chuck (I used an air drill) I spun it up and filed off the outer threads. I had to cut it off a bit too. I'm rather proud of myself for coming up with the idea of a makeshift lathe.

I found a pre-made fitting online in titanium somewhere. If someone knows of a bike with an 8mm lower link, one could probably order the through bolts for that setup.

Anybody else order one of these frames? Any updates from those that did? Do any of the vendors offer a kit for the shock mounts?

The discussions on the pivots and the shock hardware keep pushing me away from this frame, but then the prices on similar branded frames bring me back to it. That along with there's limited options for 135mm rear and standard bottom bracket since most vendors are moving on from that.

Hi guys, I have one of these also, im wondering what shocks your all using on yours?
I'm just about to order my replacement as I had a 190mm i2i on my Gary Fisher and its much bigger, it looks like it should be 184mm so im surprised at the start of the thread you put on a 165mm ???

I removed the shock and measured i2i on the frame fully extended and it was roughly 185mm, that's a big difference between that and a 165mm shock?
Has anyone tried a 184mm shock?
I'm worried about running a 165mm shock and being too slack?
Anyone else measured there frame i2i?

Could you make some pictures of the (disassembled) suspension pivots if possible? I'd like to know if there is any way to put a delrin bushing in there.

Second on additional pics of the pivots if possible. Some of the discussions about the pivots have me concerned.

I'm tempted to order one of these for the price to get me through the season till I can splurge for a carbon Tallboy build. I have a shock of my broken canzo which has the same eye to eye and should be close on the tune which should work. If they would offer a shock mount kit I'd prob give it a try but I don't want to deal with scrounging for parts to make the bike usable.

Doesn't seem like many have bought or had much to say about this frame...

If you look at my previous posts it's not such a big deal

I agree the lack of shock hardware is really annoying. I should probably talk to the folks at ICAN about it.

That said, the shock hardware isn't such a big deal. Two off the shelf hardware kits from UniversalCycles.com a couple of m8 socket head bolts an m8 lock nut and something to hold the lower bolt. If you ask nicely for $10 plus shipping I'll make you one. I wish I had stainless steel then I could try anodizing.

I really wish I had a lathe then I could be cranking these things out. I bet if someone knew what they were called we could find them online, or see if you can find a bike with m8 shock mounts and see what they used. I'm guessing something from Intense or Fisher would probably work.

Eric loves his dually and is working hard to lighten it. The weight to dollar ratio of this frame is hard to ignore especially if you have a shock laying around.

Thanks for the replies regarding the hardware. That and the pivots have me concerned. In the past budget options generally end up being more of a headache and causing more problems than money saved so I'm def hesitating. Although at $800 shipped with a headset and having a shock that should work makes it tough to pass up, I could swing a new road frame and single speed frame too for that price...

Right so today i was going to try a 184mm shock, but did get to try a few other things.
First off measured again the i2i
picked up a 165mm shock off a friend, as thats what you lot are using.
before swapping them over i measured the head angle, 75'
so i put the 165mm shock on.
so not only does it have to move quite a long way in (so loosing travel) it decreases the head angle by 5'
So i'm going to order the Monarch 184mm shock

I couldn't get the correct information.(I already had this frame before stumbling across this site) I was measuring it i2i on the frame.
But as the new shock arrived today, it definitely didn't fit, about 2mm too big.
So now going to get the Scott nude shock as that's 165 and all the internal routing is there for it.

all the internal routing for it? that's further proof that this "mystery frame" is in fact a Scott Spark copy...

It's actually more of a superfly100 copy without the ABP... the geometry matches up pretty well. But I will stay away from this frame for next couple of months, untill I know how it holds up. I'm still unsure which pivots contain bearings, and which don't.

If you have a bike where the brake and gear cables are routed underneath the bottom bracket there needs to be a loop of cable beneath the bottom bracket, so that when the suspension is fully compressed the cables don't pull tight. The cables need to be long enough so that they don't touch the frame at full compression.

If the cables pull tight when the suspension compresses then it will wear a groove in the bottom bracket shell. It can also cause ghost shifting and possibly damage the cables too.

If you have a bike where the brake and gear cables are routed underneath the bottom bracket there needs to be a loop of cable beneath the bottom bracket, so that when the suspension is fully compressed the cables don't pull tight. The cables need to be long enough so that they don't touch the frame at full compression.

If the cables pull tight when the suspension compresses then it will wear a groove in the bottom bracket shell. It can also cause ghost shifting and possibly damage the cables too.

The cables to the rear mech is fine with its internal routing but the rear brake hose needs to be about 2-3" longer. thats next weeks job.

Originally Posted by wedge

I see.

Is it possible to get the nude shock alone?

all the internal routing for it? that's further proof that this "mystery frame" is in fact a Scott Spark copy...

There is a guy selling a new one with switch gear on ebay.co.uk
Its closer to the scott than the GF with its internal cable routing and 165mm rear shock
I have a Fox RL on there at the moment and it works a treat.
Once i'm off death row (i have man flu) i will get some pictures up of the pivots etc.

It's not, but at 5.9 lb frame weight and dual suspension, does it matter that it's not carbon?

Yes, or at least for some of us. I haven't looked at this thread solely because of price or weight, but because i'm interested in the durability and ride qualities that carbon has to offer at a reasonable price.

If weight is your primary objective as mentioned there is the spearfish for the same money and the anthem x for not much more. From the talk on the $1050 Santa Cruz offering it is a budget option with a single pivot and if its anything like it's 26er version a flexy bike especially in the larger sizes. I'm not sure if the carbon frames in this thread are any better or not as there has been much feedback or comparisons but in theory this carbon frame should be much stiffer and more durable that what other $1000 offering are. Only time will tell on that one though.

yep. people need to start realize that light weight is not the only thing carbon has to offer.

Wedge I am well aware of that but I started this thread more from a price point than a carbon point of view. My 26" hardtail is carbon not al or steel because it is complient where I want it to be and stiff as a board where it should be.

The compliance of carbon is lost here because it is a thread about duallies as opposed to the other 29er cheap chinese carbon thread which is about hardtails.

The mistake I have clearly made in my last post is not appreciating how flexy the santa cruz is feared to be and if it is flexy then obviously the carbon frame will trump it. From a price perspective though my last comment stands true, at $800 + shock + pivot bearings etc, the chinese carbon duallie is no longer "cheap" in comparison to the $1050 Santa Cruz that comes with a warranty that I think most of us would trust.